--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/artifacts/src/main/java/org/dive4elements/river/artifacts/model/river/MainWstValuesCalculator.java	Thu Sep 27 18:06:26 2018 +0200
@@ -0,0 +1,115 @@
+/** Copyright (C) 2017 by Bundesanstalt für Gewässerkunde
+ * Software engineering by
+ *  Björnsen Beratende Ingenieure GmbH
+ *  Dr. Schumacher Ingenieurbüro für Wasser und Umwelt
+ *
+ * This file is Free Software under the GNU AGPL (>=v3)
+ * and comes with ABSOLUTELY NO WARRANTY! Check out the
+ * documentation coming with Dive4Elements River for details.
+ */
+package org.dive4elements.river.artifacts.model.river;
+
+import java.util.HashMap;
+import java.util.Map;
+
+import org.apache.commons.lang.math.DoubleRange;
+import org.dive4elements.artifacts.CallContext;
+import org.dive4elements.river.artifacts.model.WstValueTable;
+import org.dive4elements.river.artifacts.model.WstValueTable.QPosition;
+import org.dive4elements.river.artifacts.model.WstValueTableFactory;
+import org.dive4elements.river.model.Gauge;
+import org.dive4elements.river.model.MainValue;
+import org.dive4elements.river.model.MainValueType.MainValueTypeKey;
+import org.dive4elements.river.model.River;
+
+/**
+ * @author Domenico Nardi Tironi
+ */
+public final class MainWstValuesCalculator {
+
+    private final WstValueTable wst;
+
+    private final Map<String, MainValueQPosition> positions;
+
+    private static class MainValueQPosition {
+
+        private final Map<Gauge, QPosition> gaugePositions = new HashMap<>();
+        private QPosition refGaugePositions = null;
+    }
+
+    public static MainWstValuesCalculator forRiver(final CallContext context, final River river, final DoubleRange calcRange, final String... mainValueNames) {
+
+        final RiverInfoProvider info = RiverInfoProvider.forRange(context, river, calcRange);
+
+        return forRiverInfo(info, mainValueNames);
+    }
+
+    public static MainWstValuesCalculator forRiverInfo(final RiverInfoProvider info, final String... mainValueNames) {
+
+        final WstValueTable wst = WstValueTableFactory.getTable(info.getRiver());
+
+        final Map<String, MainValueQPosition> positions = calculatePositions(info, wst, mainValueNames);
+
+        return new MainWstValuesCalculator(wst, positions);
+    }
+
+    private static Map<String, MainValueQPosition> calculatePositions(final RiverInfoProvider info, final WstValueTable wst, final String[] mainValueNames) {
+
+        boolean isFirstGauge = true;
+
+        final Map<String, MainValueQPosition> positions = new HashMap<>();
+
+        for (final String mainValue : mainValueNames)
+            positions.put(mainValue.toUpperCase(), new MainValueQPosition());
+
+        for (final Gauge gauge : info.getGauges()) {
+
+            for (final MainValueQPosition position : positions.values())
+                position.gaugePositions.put(gauge, null);
+
+            final double gaugeKm = gauge.getStation().doubleValue();
+            for (final MainValue mv : MainValue.getValuesOfGaugeAndType(gauge, MainValueTypeKey.Q)) {
+
+                final MainValueQPosition position = positions.get(mv.getMainValue().getName().toUpperCase());
+                if (position != null) {
+                    final QPosition qPosition = wst.getQPosition(gaugeKm, mv.getValue().doubleValue());
+                    position.gaugePositions.put(gauge, qPosition);
+
+                    if (isFirstGauge)
+                        position.refGaugePositions = qPosition;
+                }
+            }
+
+            isFirstGauge = false;
+        }
+
+        return positions;
+    }
+
+    private MainWstValuesCalculator(final WstValueTable wst, final Map<String, MainValueQPosition> positions) {
+        this.wst = wst;
+        this.positions = positions;
+    }
+
+    public boolean hasPosition(final String mainValueName) {
+
+        final MainValueQPosition position = this.positions.get(mainValueName);
+        if (position == null)
+            throw new IllegalArgumentException();
+
+        return position.refGaugePositions != null;
+    }
+
+    /**
+     * Interpolates the W for a station with a fixed (virtual) wst column position
+     */
+    public double interpolateW(final double station, final String mainValueName) {
+
+        final MainValueQPosition mainValuePosition = this.positions.get(mainValueName.toUpperCase());
+
+        if (mainValuePosition.refGaugePositions == null)
+            return Double.NaN;
+
+        return this.wst.interpolateW(station, mainValuePosition.refGaugePositions);
+    }
+}
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